Abstract: With the development of sound pollutants, modern life is full of unwanted noises which are generated inside or outside of buildings and can be annoying for residents and these problems are always felt more with increased urbanization and the use of thin stone blades separators and transmission of noise from one room to another. Thus, the use of acoustic materials to counter and mitigate noise in the building is necessary. In the meantime, plaster as one of the most common building materials can be used in combination with perlite and carbon nanotubes as a proper adsorbent of sound in buildings. Accordingly, the objective of this study is to assess the degree of sound absorption by the plaster, plaster-perlite, plaster-carbon nanotubes, plaster-perlite-carbon nanotubes using conversion function in impedance tube in accordance with ISO standard number 10534-2. Empirical studies and experimental results showed that Plaster with a thickness of 12 mm can singly absorb up to 36% of noises. The results also suggest that adding perlite and carbon nanotubes results in improved sound absorption capability of plaster panel in frequency range of 100-6300 Hz, in a way that up to 65% sound absorption was observed by combining plaster perlite and up to 75% sound absorption was observed by combining. Finally, the maximum sound absorption in this study was obtained to be about 84% with simultaneous use of combination of carbon nanotubes, perlite and plaster.